Electron switching device



Jan. 18, 1944. J. w. cox 2,339,682

ELECTRON SWITCHING DEVICE Filed Sept. 5, 1941 3 Sheets-Sheet 1 *H I I I F I I I I I $2 llllmm mlmml I IIITI I INVENT OR. JOHN N. COX

M'MM/ HTTOENE Y J. W. COX

Jan. 18, 1944.

ELECTRON SWITCHING DEVICE 3 Sheets-Sheet 2 Filed Sept. 5, 1941 uNhu H u M6 Y n M m w/ofl Jan. 18, 1944. J w ox 2,339,682

ELECTRON SWITCHING DEVICE Filed Sept. 5, 1941 3 Sheets-Sheet 3 INVENTOR. JOHN M C 0X Patented Jan. 18, 1944 2,339,882 ELECTRON SWITCHING DEVICE John w. Cox, Berkeley, cant, assignor to Radio Corporation of America, a corporation of Delaware Application September 5, 1941, Serial No. 409,623

6 Claims. (01. 178-50) This invention relates to electric switchin producedby electron action.

An object of the invention is to supplant mechanical' switching devices in multiplex telegraphy by inertialess circuit closers.

More specifically, an object of the invention is to produce electron switching by polyphase electromotive forces.

Another object is to arrange blocked vacuum tubes in the circuit to be controlled and to unlock them by the electromotive force of a polyphase generator.

Another object is to produce an inertialess control of a speed correction unit in a multiplex telegraph system.

Other objects will appear in the following description, reference being had to the drawingain which: V

Fig. 1 is a circuit diagram of the transmitting apparatus, certain old and well-known apparatus being shown in block diagram.

Fig. 2 is a circuit diagram of the receiving apparatus.

Fig. 3 is a circuit diagram of the speed correction system of the driving motor in Fig. 2.

Fig. 4 gives a series of graphs illustrating the principle of operation of the invention.

In multiplex telegraph systems it is usual to assign a channel, such as a wire or radio link, to a plurality of transmitting or receiving devices in continuous succession by means of a commutator and switch arrangement moving relatively to each other. The commutator device at the receiver is maintained in synchronism with the commutator distributor at the transmitter. This is usually done by having standard frequency units that maintain the same frequency to within one part in a hundred thousand or better to produce exact proportional speed and. synchronism over a period of time. For absolute accuracy the speed of the motor driving the receiving distributor is changed by speed control unit the required amount. While these mechanical distributors have proven quite satisfactory, they nevertheless are subject to 45 wear and require expensive maintenance. It is therefore an advantage to use an inertialess distributor such as can be produced by electron action in my improvement.

Referring to Fig. 1 of the drawings, l indicates 50 the standard frequency unit, which may be of any type, and 2 a push-pull amplifier. Additional stages may be used and this is indicative only for producing power under control of the standard frequency unit at a constant frequency of alternating electromotive force. Power from the amplifier 2 is ap lied to a synchronous motor 3 which runs a' three-phase generator 4, shown with coils 5, 6 and 1 arranged in delta, but of course they could be used in a Y or star connection if desired. These coils produce electromotive forces that are 607 apart. Coil 6 is connected to the primary of transformer 8, coil 5 to the primary of transformer 9, and coil 1 to the primary of transformer I0. secondaries H and i2 of transformer v8 are connected to themput circuits of triodes l3, l4 through a suitable negative bias that normally blocks the tubes. secondaries l5 and I6 of transformer 8 are connected to similarly blocked triodes I1 and I8 in a reverse direction as compared to the connection of coils H and I2. secondaries l9 and 2c of transformer 9 are connected to triodes 2|, 22 through a blocking C battery or other negative bias, and secondaries 23 and 24 of this transformer are reversely connected to the input of triodes 25, 25 through a blocking bias. Secondaries 21, 28, 29 and 30 of transformer I0 are connected to the input of blocked vaccum tubes 3|, 32, 33 and 34 in exactly the same way as the secondaries of transformers 8 and 9 are connected to their respective tubes.

The plates of triodes l3 and H are connected together and to the cathodes of triodes l4 and I8. These electrodes are then connected to tongue 40 by line 46. The plates of triodes 2| and 25 are similarly connected together and to the cathodes of triodes 22 and 26. They are also connected by line 41 with tongue 4|. The plates of triodes 3| and 33 are likewise connected together and to the cathodes of triodes 32 and 34. These electrodes are then joined by line 48 W1 tongue 42.

Reference characters 35, 36 and 31 indicate any type of automatic transmitter such as a tape transmitter, well known in the art. These transmltters have circuit closers maintained at the same speed and phase, as well known in the art. This is indicated for convenience of illustration by a synchronous driving motor 38 operated from the generator 4, although any type of motor control may be used, such as disclosed in the patent to Callahan et al., 2,010,505, August 6, 1935, for example. The switching mechanism manipulated by the driving motor 38 is diagrammatically illustrated as tongues 40, 4| and 42 operated in unison to alternately engage plus and minus contacts connected to suitable batteries 43, 44 and 45. These batteries have the center grounded, as usual. It will be understood that the switch tongues that alternate towards the plus and minus contacts in each tape transmitter make electrical contacts under control of perforations in the tape. This has not been illustrated, as it is a well-known action and there is no need to complicate the drawings by showing this portion of the prior art.

The cathodes of tubes l3, l1, 2|, 25, 3| and 33 are connected to conductor 49, which connects to a Finch locking circuit and the keyer indicated by block diagram 50. This locking circuit and keyer is a well-known construction and a description may be found in Finch Patent 1,844,950; February 16, 1932, and its specific application to a multiplex telegraph system is fully described in MathesPatent 2,214,642, September. 10, 1940, page 4, commencing at line 59. This.

manner of controlling a radio transmitter or wire line, per se, is not my invention and hence it need not be described. The output of thelockerators, 53, 54 and 55, which are not in exact phase. Generator 54 leads generator I3 slightly, while generator 55 lags generator 53 by an equal angle. l

The stator of synchronous motor 52 is rotatable for speed control-purposes. This stator is rotated a slight amount by two correction A. C. motors 56, 5611, the gearing being such that the adjustment made by the correction motor holds.

' assassa 4 vacuumgtube 33 has its cathode connected to ground through a suitable bias resistance 12a. Ground is the usual plus or minus terminal of the'battery, as shown. The plate of this tube is connected through resistance 13 to the posit'lve' terminal of the battery and also to the con- .ductor 46 connected to the 'plates of tubes I4,

This can be accomplished, for example, by making it of the worm and gear type. A. 0. motor 56, when energized, rotates the stator, say, clockwise when the motor 52 lags slightly the motor 3 at the transmitter, while motor 55a rotates the stator counterclockwise when the receiving motor leads. This brings the receiving motor into correct phase and speed.

The three-phase generator 53 has one phase connected to transformer 51, another to transformer 58, and the remaining phase to transformer 59. These three transformers each have secondaries connected to vacuum tubes exactly in the same way as-.described in connection with Fig. 1 and they and their connection secondaries have been given the same reference characters as in Fig. 1. In view of this, the connections will be understood without repeating them in detail. The conductor 43 in Fig. 2 connects the plate. of tube l3 to a Finch locking circuit I, which as stated is a well-known switching device. The output of this locking circuit is connected to any utilization device. 5|, for example a siphon recorder. The conductor connected to the plate oftube 2| is joinedtotheline 4| andthis line is connected to the locking circuit 62, whichmay be the same as locking circuit 60. Hence the circuit has not been shown in detail. The output of locking circuit this connected to utilization device 63. The conductor connected to the plate 4 of tube 3| is connected to line 43 and this line is connected to locking circuit 54, similar to the looking circuit 33, and the output of this locking.

circuit is connected to utilization device 55.

The receiving station employing the usual amplifiers, detectors and other devices, is not shown in the drawings, as it may be of any desired form.

shown in Fig. 2 butillustrated in Fig. 3. The

I332, 23,- and 34, as well as to the other parts, as previously described in connection with Fig. 1. 63 is biased so that the plate current is small and normally produces only a small drop in resistance 13. Tubes 2|, 22, 25 and 25 have their plates and cathodes similarly connected to locking circuit 52 by conductor 41, and tubes 3|, 32,-," and 34 are connected in a similar way to locking circuit 54 by conductor 48. I

3 the three-phase generators 54, 55 are indicated by their armature coils. In this figure there are six separate transformers, instead of three as in Figs. 1 and 2. Leading generator 54 hasdts armature coils 80, 8| and 82.connected respectively to the primaries of transformers 14, I5 and II. Lagging generator 55 has its armature coils l3, l4 and connected respectively to the primaries of transformers l5, l1 and 13. The? twelve secondaries of the six transformers are connected to the input circuits of the tubes, half-.beingreversed as shown in Fig. 2. ,These secondaries and tubes have been given the same reference characters as in Figs. 1 and 2 and the grid. voltages-in all of the tubes normally block the; tubes as in the other figures. The plates of allltubes are connected together and to the lower 'endpf secondary coil 81. The other end of coil fliis connected to an intermediate point of resistance It- The cathodes of tubes I 3, l4, 2|, 22, 3| 32 are connected together and to the upper end 'of resistance 86. The cathodes of tubes II, ll, 2i, 2', .33 and. 34 are connected together and to the lower end of resistance 35.

The signal input H (see Fig. 2 also) is connected to the grid 'of tube 88, having its cathode grounded. The output circuit of the tube includes the primary coil 89 of the transformer hav-- in the secondary 81,

Push-pull stage 90 has an alternating current of, say, 60 cycles fed to the input circuit through transformer 3|. An intermediate point of the secondary-of this transformer is connected to the-*upper end of resistance 86 and the joined cathodes ofthis stage are connected to the intermediate point of this resistance through blocking negative bias source 90a. The output of this stage is fed through transformer 92 to alternatinglzcurrent motor 56. Push-pull stage 93 similariy has 60"cycie alternating current fed to its input circuit, through transformer 94. An intermediate point'of the secondary of this transformeris connected to the lower end of resistance ":and the joined cathodes are connected to the intermediate-point. The secondary of the output transformer of push-pull stage 93 is connected to alternating current motor 56a.

The operation will now be described.

Referring 'to Fig. 1, synchronous motor 3 will runat a substantially constant speed by operationof the standard frequency unit and push-pull stage 2. This will produce a three-phase voltage in generator 4, as indicated in Fig. 4. This generatormay-be designed, if desired, to produce moresharply peaked voltages than usual in wellknown ways; one being described in the patent to 1"inch,'1,844,950-'though this peaked form of wave is not essential. Let it be assumed that channel No.1 is connected to tape transmitter 35, channel No.2 to tape transmitter 33, and channelNo. 9 to tape transmitter 31 and that the outgoing line 49 is to be assigned to these channels in regular succession at equally-spaced time intervals by my improved inertlaless distributor.

Current will pass from channel No. 1 for the brief instant at the peak I of the voltage produced by phase'No. 1 (coil 6) of generator 4 in the primary oi transformer B. As previously explained, all of the twelve tubes have sumcient negative bias to carry them below the blocking point. If we assume that the time of the voltage peak' I00 has just arrived in 'the secondary of transformer 8, tube I3 will be unblocked by the voltage and current will pass from the positive terminal of battery 43, assuming that tongue 40 engages the positive terminal due to perforation in the tape, to the plate of tube I3, to its filament and hence to conductor 49 to the usual locking circuit and keyer, which will send out a signal through the transmitting apparatus in a wellknown way. This is a well-known operation and need not be described. The action, however, is described in the above-mentioned Mathes Patent 2,214,642. It will be noted that tongue 40 is also connected to the plate of tube II, but at this time current cannot pass through tube II becaus the coil I5 is reversely connected to the input circuit and the peak of the voltage wave I00 merely gives the blocked tube a still greater negative voltage. If tongue had been in contact with the negative terminal for a space signal, current would have flowed from the i terminal of the battery 43 through keyer 50 and tube I4, tube I8 being blocked in this half cycle.

When the peak IOI of phase No. 2 (coil 5) of generator 4 arrives in transformer 9, assuming that tongue 4| engages the positive terminal in the tape transmitter, current will pass from the positive terminal of battery 44 through the tongue and through the plate-cathode circuit of tube 2| to line 49 and thence to the locking and keying circuit, as previously referred to for channel No. 1. Current at this time cannot pass through tube 25 because of the reversed input connections.

When the peak I02 of the third phase (coil 1) of generator 4 arrives in transformer I0, assuming that tongue 42 has engaged the negative terminal in the tape transmitter, because of the absence of a perforation, current will pass from the "plus or minus terminal to ground through locking circuit 50, conductor 49, through the plate-cathode circuit of tube 32 to tongue 42 and the negative terminal. Current cannot pass through tube 34 at this time, because the reversed coil connection merely increases the blocking potential of the tube.

At the next instant, negative peak I03 of the first phase of generator 4 arrives in transformer 8. This more strongly blocks tubes I3 and I4 and unblocks tubes I1 and I8. Current can flow to the locking circuit through tube I1 and not through tube I3, if tongue 40 is in engagement with the positive terminal in the tape transmitter through a perforation. If the signal mark terminated and the negative terminal were engaged by the tongue, current would have to pass from the plus or minus terminal through tube I8, as previously described for the positive half cycle in connection with tube I4. In like manner, peaks I44 and I05 of the second and third phases of generator 4 will connect, or switch, by electron means, channels No. 2 and No. 3 to the outgoing line for a mark or a space signal, as the case may ' At the receiving station the standard frequency unit I will maintain the speed fairly constant over a considerable period of time, but to maintain it exactly constant the correction unit is used. Inasmuch as correction takes place after-only a small departure from synchronis'm, the correction unit is in reality a phase corrector. This speed or phase corrector is shown in Fig. 3, but before explaining its operation correct phase condition will be assumed in explaining the switching arrangement of 'Fig. 2.

It will be assumed that tube I08 is conducting and tube I09 blocked. Condenser I06 is assumed to be fully charged, due to the low drop in resistance I3 of the plate circuit of tube 89. Assuming that a D. C. mark from channel No. 1 has arrived, a direct current drop is produced in resistance 31 and this drop charges condenser I0. During the charging of the condenser a voltage drop is produced in resistance I2, making the, grid of tube 89 positive. This increases the transconductance of the tube and a sudden drop is produced in resistance I3. This lowers the voltage opposed to the charge in condenser I06 and it suddenly discharges through conductor 49, vacuum tube I3, the plate-cathode circuit of tube 69 to ground and through the right-hand half of the B battery and the grid resistance I01 of the locking circuit 60. This results. because at this time'tubes I3 and I4 are unblocked by the peak I00 (Fig. 4) produced by coil H0. The sudden lowering of the grid potential by the drop in resistance I01 blocks tube I09 and this automatically causes tube I09 to conduct, due to the connection of the grid of tube I09 to the plate of tube I08. This reverses the potential applied to utilization device 6| and a mark signal is sent thereto.

Since a mark signal was also assumed for channel No. 2, due to the drop in resistance 01 the locking circuit will now be unbalanced and a mark signal will be produced in device 93. When peak I02 arrives, the assumed space signal of channel No. 2 arrives and the drop in resistance 61 is reduced to zero or is reversed and condenser I0 discharges. A negative potential from the drop in resistance I2 is applied to the grid of tube 69, reducing the current to a minimum. This lowers the drop in plate resistance 13 and again applies practically full potential to condenser I00 through tube I4. Condenser I04 now charges and produces a drop in resistance I0'I that applies a positive potential to the grid of tube I00. Tube I08 instantly conducts and simultaneously blocks tube I09, due to the lowering of the potential on its grid. This reverses the output potential and a space signal is sent to utilization device 05.

Negative peaks I03, I04 and I05 act in the same way, except tubes I'I, I8, 25, 26, 33 and 34 are unblocked for passage of current and the other tubes are maintained in blocked condition.

Thus it will be seen that the generator 53 commutes or switches the signals to the utilization devices in unison with the commutation at the transmitter.

Let it now be assumed that the standard frequency unit at the receiver lags slightly the unit at the transmitter. When a composite mark or space begins, a sudden change of potential will appear at the grid of tube 88. The connections could be arranged for either, but let it be assumed that the circuit is such as to utilize the voltage change produced at the beginning of the mark and that the change of potential on the grid oi tube 88 causes a positive potential kick to appear at thelower end of secondary coil 81. Since there is a lag in phase between the local Ire-- quency and the signal, this kick will appear at the peak lflflb, llllb or I02?) 01 generator 54. Assume that it is lllllb. The short kick will cause a pulse to flow through tube ii to theupper end of resistance 86 and thence to the other terminal of coil 81 through the midtap connection of the resistance. The drop in the upper half or resistance 88 will thus be applied to the input electrodes of the tubes or push-pull stage 90. The positive potential on the grids will overcome the blocking bias o1 bias source 90a and 60 cycle alternating voltage from transformer ill will produce an alternating voltage in the output transformer 92 and operate motor 56. This will rotate the stator of motor 52 clockwise (see also Fig. 2) and kick the rotor forward to reduce the lagging of the rotor behind the incoming signals.

It the departure from correct phase is sumcient, additional kicks from the succeeding mark signals will pass through the tubes to alter the speed until correct phase is produced.

If the standard frequency unit at the receiver leads the one at the transmitter, the potential kick in secondary 8'! will arrive when peak Nina, lflla or I021: is produced in generator 55. Assume it is lllfla. In this case, the potential kick from coil 81 will cause a current pulse to pass through tube H to the lower end of resistance 88 to the mid-point and back to the other end of secondary 81. This will place a sulllcient positive, or reduced negative, potential on the grids of push-pull stage 93 to produce 60 cycle voltage in the circuit of motor 56a. This motor will rotate the stator of motor 52 counterclockwise and kick the rotor of that motor backwards to slow down generator 53. This continues at the beginning and end of each composite mark until exact synchronism of phase is obtained, but the potential kick will send current to the resistance 86 through the tube corresponding to the channel transmitting the particular signal.

In the drawings I have omitted the heaters for the unipotential cathodes oi thevacuum tube, but it will be understood that these will be used and energized in the usual way. It will be apparent that other types of tubes may be used 2. In a three-channel multiplex system, a composite channel line, a three-phase alternating current generator, three pairs of electron tubes, means for connecting the input circuit of the tubes of each pair to the terminals of a separate phase or said generator, the connection or one circuit being reversed in respect to the for connecting the input circuits of the tubes of with any desired number of electrodes, as the invention is not dependent upon the action of any particular type.

The invention is not to be limited to the particular embodiments disclosed, as these have been given by way of example.

Having described my invention, what I claim is:

1. In a multiplex system, a composite channel line, a polyphase alternating current generator, a plurality of pairs of electron tubes, means for connecting the input circuits oi the tubes 01 each of the pairs to the terminals or a separate phase of said generator, the connection of one circuit being reversed in respect to the other, means for providing a negative bias in each of said input circuits having a value less than the maximum value of the alternating voltage of said generator, a plurality of signal devices and means for connecting each device to said composite line through an output circuit or one of the tubes of a separate one of said pairs.

one of said quartets to the terminals of a separate phase of said generator, the connections of the input circuits of a pair of the tubes in each quartet being reversed in respect to those of the remaining pair, a plurality of signal devices and means for connecting each of said devices to the anodes of the tubes of one of the pairs of a separate one or said quartets and to the cathodes of the remaining pair thereof.

4. In a three-channel multiplex system, a composite channel line, a three-phase alternating current generator, three quartets of electron tubes, means for connecting the input circuits of the tubes of each of said quartets to the terminals of a separate phase of said generator, the connections of the input circuits of a pair of the tubes in each quartet being reversed in respect to those of the remaining pair, three signal devices and means for connecting each of said devices to the anodes or the tubes of one of the pairs of a separate one of said quartets and to the cathodes of the remaining pair thereof.

5. In a three-channel multiplex system, an

outgoing line, a three-phase alternating current generator, three pairs of electron tubes, means for connecting the input circuits of the tubes of each of said pairs to the terminals of a separate phase of said generator, the connections of one input circuit being reversed in respect to the other, three signal transmitters, each having a movable tongue and two cooperating contacts of different polarity, and means for connecting the tongue of each transmitter to said line through the output circuit of the tubes of a separate one of said pairs. 6. In a three-channel multiplex system, an outgoing line, a three-phase alternating current generator, three pairs of electron tubes, means for connecting the input circuits of the tubes of each of said pairs to the terminals Of a separate phase of said generator, the connection of one input circuit being reversed in respect to the other, a negative bias in each of said input circuits having a value less than the maximum value of the alternating voltage of said generator, three signal transmitters, each having. a movable tongue and two cooperating contacts of different polarity, and means for connecting the tongue of each transmitter to said line through the output ciiriciuit of the tubes of a separate one of said p s.

JOHN W. COX. 

